The present invention relates to a modified polyolefin-polyester graft copolymer effective as a compatibilizer for polycarbonate resins and polyolefins, and a method of producing such modified polyolefin-polyester graft copolymer, and more particularly to a graft copolymer of a polyester having particular intrinsic viscosity [.eta.] and end carboxyl group content and a modified polyolefin having epoxy groups or carboxyl groups, and a method of producing such a graft copolymer. It further relates to a polycarbonate-polyolefin thermoplastic resin composition containing such a graft copolymer with a well-balanced combination of rigidity, impact resistance, thermal deformation resistance, moldability, surface peel resistance, solvent resistance, etc.
Aromatic polycarbonates have excellent impact strength, heat resistance, rigidity and dimension stability, but they are poor in solvent resistance and moldability. To overcome these problems, attempts have been made to provide polycarbonate compositions with polyolefins. However, since polyolefins and polycarbonates do not have good compatibility, proposals have been made to add various third components to improve their compatibility.
Japanese Patent Laid-Open No. 57-108151 discloses a polycarbonate resin composition comprising 100 parts by weight of a polycarbonate resin, 0.3-20 parts by weight of polyethylene and 0.3-20 parts by weight of a butyl rubber.
Japanese Patent Laid-Open No. 57-108152 discloses a polycarbonate resin composition comprising 0.3-20 parts by weight of an ethylene-propylene copolymer and/or an ethylene-propylene-diene copolymer as a third component.
Japanese Patent Laid-Open No. 57-111351 discloses a polycarbonate resin composition comprising 0.3-20 parts by weight of an isoprene rubber and/or a methylpentene polymer as a third component.
The polycarbonate resin compositions disclosed in Japanese Patent Laid-Open Nos. 57-108151, 57-108152 and 57-111351, however, suffer from drastic decrease in impact strength and surface peel of molded products when polyolefin content increases.
Japanese Patent Laid-Open No. 61-215649 discloses a polycarbonate-polyolefin composition comprising as a third component an olefin-vinyl ester copolymer, for instance, an ethylene-vinyl acetate copolymer [EVA resin], etc.
However, this composition also shows poor impact strength due to the low compatibility of the polycarbonate and the polyolefin, suffering from surface peel, although it has relatively good solvent resistance.
Japanese Patent Laid-Open Nos. 61-225245, 61-235456 and 61-238847 disclose compositions comprising aromatic polycarbonates, polyesters and/or modified polyolefins, etc. However, since no unmodified polyolefin is contained in these compositions, they are poor in solvent resistance.
As described above, although thermoplastic resin compositions based on polycarbonates and polyolefins whose compatibility is improved and which passes an excellent balance of mechanical strength, moldability, solvent resistance, etc. are desired for automobile parts, etc., satisfactory compositions have never been provided.